Heavy oil conversion

ABSTRACT

A PROCESS FOR OBTAINING INCREASED NORMALLY LIQUID HYDROCARBON YIELDS FROM COKING A HYDROCARBON FEED CONTAINING AT LEAST THREE PARTS PER MILLION METALS WHICH PROCESS COMPRISES: (A) CONTACTING THE FEED, AT ELEVATED TEMPERATURE AND PRESSURE AND IN THE PRESENCE OF ADDED HYDROGEN, WITH A HYDROTREATING CATALYST COMPRISING GROUP VI AND GROUP VIII MEATAL AND AN INORGANIC REFRACTORY BASE, AND HAVING AT LEAST 50 PERCENT OF ITS PORE VOLUME FROM PORES 100 ANGSTROMS OR LARGER IN PORE DIAMETER TO OBTAIN A HYDROTREATED FEEDSTOCK, AND (B) COKING AT LEAST A PORTION OF THE HYDROTREATED FEEDSTOCK AT A TEMPERATURE BETWEEN 700*F. AND 1100*F. TO OBTAIN SOLID COKE AND VAPORIZED NORMALLY LIQUID HYDROCARBONS. PREFERRED HYDROTREATING CATALYSTS FOR USE IN THE PROCESS ARE OBTAINED BY EXPANDING THE CATALYST DURING CATALYST PRODUCTION BY ADDING A HIGH MOLECULAR WEIGHT DETERGENT TO THE CATALYST HYDROGEL BEFORE THE HYDROGEL IS DRIED AND CALCINED. ALSO, IT IS PREFERRED TO USE A COMMON FRACTIONATION ZONE FOR BOTH THE HYDROTREATING STEP AND THE COKING STEP AND TO ELIMINATE VACUUM DISTILLATION AHEAD OF THE HYDROTREATING STEP.

A08- 15 1972 R. R. RosELlus HEAVY OIL CONVERSION Filed Jan. 21, 1971 INVENTOR RONALD R. ROSEL IUS a L mrow E QN w Q w N I. l W. m t S N mzoN A mzoN A ozmwmwf I A ozoo zoF zoFu -E omer WN Wx Q ...IO mODmU Wi 478% Q24 56%@ ATTORNEYS mODmU MV fm! United States Patent @Hee 3,684,688 Patented Aug. 15, 1972 3,684,688 HEAVY OIL CONVERSION Ronald R. Roselius, Richmond, Calif., assignor to Chevron Research Company, San Francisco, Calif. Filed Jan. 21, 1971, Ser. No. 108,378 Int. Cl. Cb 55/00; C10g 23/02; B01d 11/82 U.S. Cl. 208-50 10 Claims ABSTRACT OF THE DISCLOSURE A process for obtaining increased normally liquid hydrocarbon yields from coking a hydrocarbon feed containing at least three parts per million metals which process comprises: (a) contacting the feed, at elevated temperature and pressure and in the presence of added hydrogen, with a hydrotreating catalyst comprising Group VI and Group VIII metals and an inorganic refractory base, and having at least 50 percent of its pore volume from pores 100 angstroms or larger in pore diameter to obtain a hydrotreated feedstock, and (b) coking at least a portion of the hydrotreated feedstock at a temperature between 700 F. and ll00 F. to obtain solid coke and vaporized normally liquid hydrocarbons. Preferred hydrotreating catalysts for use in the process are obtained by expanding the catalyst during catalyst production by adding a high molecular weight detergent to the catalyst hydrogel before the hydrogel is dried and calcined. Also, it is preferred to use a common fractionation zone for `both the hydrotreating step and the coking step and to eliminate vacuum distillation ahead of the hydrotreating step.

BACKGROUND OF THE INVENTION The present invention relates to coking, particularly coking of metals-contaminated hydrocarbon feedstocks. The present invention also relates to the combination of hydrotreating and coking and fractionation facilities.

Various types of coking processes are known, including delayed coking, moving bed coking and fiuidized coking. Furnace type coking units are called delayed cokers because they heat the residuum or other hydrocarbon feedstock to coking temperatures so rapidly that little reaction occurs while the charge is in the furnace. Efuent from the furnace discharges at about 850 F. to 1000 F. into a large coke drum, where it remains until it either cracks and passes off as vapor or condenses into coke. Coke drums operate at pressures in the range of lO to 150 p.s.i.g. Because the reaction is endothermic, vapors leave the coke drum at about 800 to 850 F. When a coke drum is lled, the furnace effluent is diverted to another drum, and the coke is removed from the rst one.

Among the moving bed coking processes which have been developed are contact coking in the U.S.A. and the Hoechst process in Germany. In both processes the product coke particles constitute the circulating heat carrier. However, in contact coking, heat is supplied by burning part of the coke in the preheater, whereas the Hoechst process employs indirect exchange with llue gas in tubes in the preheater. Also, mass lift is used in the contact process, ygas lift in the Hoechst process. Moving bed coking processes are described in Petroleum Reiiner, 34(l0):l39 (1955); and Petroleum Engineering, 26 (8):C-10 (1954).

Fluidized beds are also used in coking heavy oil feedstocks such as residuum feedstocks. As with moving beds, the product coke is circulated through a burner and a reactor, and high reaction temperatures are possible. Steam is used to uidize the coke` fbed in thereactor.

Typical reactor conditions are 925 F., and 5 to l0 p.s.i.g. Because the coke particles grow during the operation, a portion of the circulating solids may be drawn off (in addition to the net coke production), ground, and returned to the unit as seed coke. Sufficient seed coke is recycled to hold the circulating solids in the desired size range. The size of the circulating coke may also be controlled by the use of an elutriator. The net coke production is withdrawn from the elutriator as large particles, and the finer particles are recycled to the reactor.

Coking is generally applied to the conversion of feedstocks such as vacuum residuum to coke and suitable charge for a hydroconversion step such as hydrocracking and hydrodesulfurization or as a charge for catalytic cracking or catalytic reforming. For example, U.S. Pat. 2,727,853 describes a process for the upgrading of heavy oils wherein effluent from a delayed coking step is passed to catalytic polymerization and vapor phase hydrogenation with a portion of the hydrogenated material being passed to catalytic cracking. According to the process disclosed in U.S. Pat. 2,727,853, asphaltic material from a propane deasphalting step ahead of the delayed coking step is fed to the coking step. Effluent from the coking step can be fed in part to the propane deasphalting step with the deasphalted material from the propane deasphalting step being fed to catalytic cracking, U.S. Pat. 3,238,117 and U.S. Pat. 3,493,489 also disclose coking ahead of a hydroconversion step, particularly coking ahead of hydrocracking. U.S. Pat. 2,988,501 and U.S.` Pat. 3,027,317 disclose coking ahead of hydrodesulfurization.

U.S. Pat. 2,871,182 discloses hydrodesulfurization ahead of coking. According to the U.S. Pat. 2,871,182 disclosure, any sulfactive catalyst such as cobalt and molybdenum oxides on alumina can be used for the desulfurization step ahead of coking. The metals content of the feed to the U.S. Pat; 2,871,182 process is not given.

SUMMARY oF THE INVENTION According to the present invention, a process is provided for obtaining increased normally liquid hydrocarbon yields from coking a hydrocarbon feed containing at least three parts per million metals which process comprises: (a) contacting the feed, at elevated temperature and pressure and in the presence of added hydrogen, with a hydrotreating catalyst comprising Group VI and Group VlII metals and an inorganic refractory base, and having at least 50 percent of its pore volume from pores 100 angstroms or larger in pore diameter to obtain a hydrotreated feedstock, and (b) coking at least a portion of the hydrotreated feedstock at a temperature between 700 F. and 1100 F. to obtain solid cokeand vaporized normally liquid hydrocarbons.

In the process of the present invention, I have found that unexpected yields of normally liquid hydrocarbons are obtained from the coking step when using certain expanded catalysts in the hydrotreating step preceding the coking step. The term normally liquid is used herein to mean hydrocarbons which exist in the liquid form at room temperature and pressure, i.e.,about F., and atmospheric pressure. The use of catalysts having relatively large pore sizes is particularly important in the process of the present invention as opposed to the use of general hydrotreating catalyst particles which usually have average pore sizes considerably below angstroms in diameter. The pore size of the catalyst can be calculated by various methods, usually assuming the pores in the catalyst can be treated as approximately cylindrical. Pore size distribution can be obtained, for example, by capillary condensation methods as described, for example, by

E. P. Barrett, L. G. Joyner, and P. H. Halenda in the Journal of the American Chemical Society, vol. 73, p. 373 (1951). Larger pore sizes, usually in the range of 100 angstroms and larger, are frequently determined by a pressure porosimeter method described, for example, by H. L. Ritter and L. C. Drake in Industrial and Engineering Chemistry, vol. 17, p. 782 (1945).

Various methods can be used to obtain the hydrotreating catalyst of larger than average pore diameters for use in the hydrotreating step of the present invention. For example, commonly assigned application Ser. No. 774,203, led Nov. 7, 1968, and now abandoned, discloses that optimum catalyst properties, including increased pore sizes may be obtained by adding titania, Alundum particles, or recycle catalyst lines to the catalyst during the process of forming a catalyst. Also, Ser. No. 778,332, filed Nov. 22, 1968, now U.S. Pat. 3,577,353, discloses a process for producing catalysts of increased pore size obtained by extracting the catalyst with an alcohol, such as methanol, during manufacture of the catalyst particles. The disclosures of the two aforesaid patent specifications are incorporated by reference into the present patent application.

Johnson and Mooi, in the Journal of Catalysis, 10, 342-354 (1968), discuss pore distribution in alumina catalysts. In their discussion, reference is made to treating alumina gels with methanol to exchange methanol for water in the alumina gels. The catalyst obtained upon drying and calcining had larger pore sizes than for those catalysts which were not treated with methanol to replace water prior to drying and calcining.

A particularly preferred method for producing catalysts with larger average pore diameters is described in commonly assigned application Ser. No. 3,239', the disclosure of which application is incorporated by reference into the present specification. The expanded (or increased pore size) catalyst production process described in Ser. No. 3,239 comprises (a) forming a hydrogel comprising at least one inorganic compound (which is typically converted to an oxide upon subsequent calcination), (b) adding a detergent to the hydrogel, and (c) carrying out at least part of the drying of the hydrogel after the detergent is added to the hydrogel.

Particular hydrotreating catalysts which can advantageously be expanded in accordance with the above process include composites comprising discrete substantially insoluble metal phosphate particles surrounded by a continuous phase matrix comprising at least one solid oxide and at least one hydrogenating component selected from Group VI-B metals, and compounds thereof, and Group VIII-B metals, and compounds thereof. Particularly preferred catalyst composites for production in expanded form for use in the process of the present invention are described in more detail in U.S. Pat. 3,493,517, the disclosure of which patent is incorporated by reference into the present specification. The hydrotreating catalysts to which U.S. Pat. 3,493,517 is directed are particularly preferred for use in the process of the present invention for reasons including the following reasons:

(l) the hydrotreating catalyst containing metal phosphates in a continuous phase matrix of other catalyst components as described in U.S. Pat. 3,493,517 can be readily expanded using methods such as the use of a high molecular Weight detergent as described in Ser. No. 3,239;

(2) the metal phosphate particles in the catalyst to which U.S. Pat. 3,493,517 is directed appear to contribute both to larger pore sizes of the catalyst composite and to enhanced hydrotreating activity for the catalyst;

(3) in addition to the increased metals capacity for the expanded or relatively large pore-sized catalyst, the stability of the catalyst is relatively high in hydrotreating, particularly hydrodesulfurizing, metals-contaminated heavy feedstocks, such as residuum feedstocks, so that the catalyst can be kept on-stream at high activity ahead 4 of the coking step of the present invention for relatively long periods of time.

In the process of the present invention, although it is particularly important to use a catalyst having relatively large pores, it is also preferred to use a relatively high hydrogenation activity catalyst, particularly a catalyst having a high activity for hydrodesulfurization and hydrodemetallation of heavy feedstocks. It is strongly preferred that the catalyst used in the process of the present invention have high activity for hydroconversion of asphaltenes and hydrogenation of aromatics.

In order to achieve a high activity for hydrotreating reactions such as hydrogenation, hydrodesulfurization, hydrodenitritication and hydrodemetallation, as opposed to only a high capacity for demetallation, it is usually preferred to use catalyst composites having a surface area of at least square meters per gram of catalyst. Using the expansion methods as described in Ser. No. 3,239, average pore diameters 0f 100 angstroms and larger can be obtained while still producing catalyst particles having a surface area above 100 or 200 square meters per gram as, for example, 275 square meters per gram.

For the hydrotreating step of the process of the present invention, it is preferred to use a hydrotreating catalyst bed as described in `U.S. Pat. 3,496,099 in order to reduce the rate of pressure drop build-up due to the deposition of metals, particularly iron, when hydrotreating the residuum feedstock ahead of the coking step. Thus, when using one or more xed catalyst beds with the hydrotreating step of the present invention, it is preferred to pass the hydrocarbon feed together with hydrogen through a first or initial catalyst bed or layer having increasing hydrogenation catalytic activity along the normal direction of feed ow through the bed or layer. Other preferred methods for carrying out hydrotreating, particularly hydrodesulfurization simultaneously with hydrodemetallation of heavy feedstocks such as atmospheric residuum or vacuum residuum, are described in commonly assigned applications Ser. Nos. 2,096 and 2,097. The disclosures of U.S. Pat. 3,496,099 and Ser. Nos. 2,096 and 2,097, particularly those portions of the latter two applications relating to the porosity of the catalyst used for simultaneous hydrodesulfurization and hydrodemetallation, are incorporated by reference into the present specification.

The process of the present invention is applied to heavy oils or residuum feedstocks containing three parts per million metals present as soluble organometallic compounds, and usually 20-200 parts per million metals. The term metals is used herein (in reference to metals in the hydrocarbon feedstock to the hydrotreating step) to mean metals selected from the group consisting of iron, nickel, and vanadium. Other metals may also be present, such as sodium and calcium, but the term metals is not used in the present specification to include metals outside the iron, nickel, and vanadium group. Iron, nickel, and vanadium, which are frequently present in residuum feedstocks to a substantial extent, present a diicult problem in hydrotreating processes as the metals are usually in large part converted from the soluble organometallic form during the hydrotreating reactions to insoluble elemental and sulfided forms which plug up and otherwise foul the catalyst particles used in the hydrotreating step.

However, the preferred catalyst used in the hydrotreating step, particularly expanded hydrogel catalysts containing at least 200 m.2/g. of surface area but also containing a substantial amount of pores having a diameter of 100 angstroms or greater, operate to achieve high hydrogenation (and hydrodesulfurization) activity as well as high hydrodemetallation activity and capacity.

Thus, the process of the present invention is particularly advantageously applied to a residuum feedstock containing at least 0.5 weight percent sulfur present as organic sulfur compounds, and usually between about 1.0 and 7 weight percent sulfur in addition to a substantial quantity of metals contaminants. Also, the preferred expanded catalysts, as indicated previously, operate in a surprising cooperative manner with the subsequent coking step to achieve considerably greater yields from the coking step than would be expected on the basis of the boiling range of the feed fed to the coking step.

A very important aspect of the preferred large-pore catalysts used in the hydrotreating step is their high capability to reduce the asphaltenes (normal-pentane insoluble constituents) of the residuum hydrocarbon feed to the hydrotreating step by at least 25 percent and, more preferably, about 40 percent or more as, for example, from an asphaltene weight percent of about percent to an asphaltene weight percent of about 2.5 percent. Heavy oil eflluent from the hydrotreating step of substantially reduced asphaltene content has been found to result in particularly high liquid yields from coking of the reduced asphaltene content heavy oil.

Preferably, the coking step utilizes a delayed coking process with a furnace outlet temperature of about 900 to 1100 F., and a coking temperature for the coking drum between about 700 and 900 F.

We have found that the hydrotreating step and the coking step of the present invention are advantageously integrated by feeding long residuum derived from a crude oil feedstock directly to the hydrotreating step without any vacuum distillation and with at least a portion of the hydrotreating step eluent being fed to the coker main fractionation column. The coker fractionation column thus receives effluent from the hydrotreating step as well as coker oil eluent from the coking step.

Particularly in the case of delayed coking, itis preferred to use vaporized normally liquid hydrocarbon eluent from the coke drum as a stripping medium in the coker fractionation column which receives the etiiuent from the hydrotreating step. In this manner, the coker fractionation column serves multiple purposes, operating in part as a replacement for the normal vacuum distillation column, and also as a main rough fractionation column for the euent from the hydrotreating step, and as a fractionation column for the effluent from the coking step. Products from the coker fractionator or common fractionation column usually include a gaseous stream, a gasoline stream which can be further upgraded as, for example, by catalytic reforming, and a gas oil stream which can be further upgraded as, for example, by hydrotreating or by hydrocracking and/or catalytic cracking.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a process flow diagram schematically indicating a preferred embodiment of the process of the present invention.

DETAILED DESCRIPTION Referring now in more detail to the drawing, a crude oil is fed to crude oil fractionation zone 2 via line 1. In addition to crude oil, other hydrocarbon sources such as shale oils and oils derived from coal can be fed to fractionation zone 2; crude oil represents a preferred and typical feedstock for the process of the present invention. Crude oil fractionation zone 2 can consist of various fractionation columns such as an atmospheric crude oil distillation column followed by a vacuum distillation column receiving reduced crude from the bottom of the atmospheric distillation column. However, in accordance with a preferred embodiment of the present invention, fractionation zone 2 consists basically of an atmospheric distillation column with the typical vacuum distillation column being omitted. A reduced crude or long residuum is withdrawn from the bottom of the atmospheric distillation column in zone 2, via line 3, and is fed to hydroconversion zone 4. Lighter products including, for example, .a naphtha product and a gas oil product are withdrawn via lines 5 and 6 from fractionation zone 2.

Hydroconversion zone 4 must contain catalyst particles having relatively large pore diameters as this is a critical aspect of the process of the present invention. The hydroconversion zone can serve primarily to hydrodemetallate the long residuum feed to zone 4 by contacting the feed at elevated temperature and pressure and in the presence of hydrogen added via line 7 with a hydrotreating catalyst comprising Group VI and Group VIII metals and an inorganic refractory base. The hydrotreating catalyst preferably is used to accomplish at least some desulfurization of the residuum feedstock introduced via line 3 in addition to accomplishing the removal of 25-5 0 weight percent or more (e.g., up to or 90 wt. percent) of the metals in the residuum feedstock. 'Ihe catalyst used in the hydroconversion zone should have at least 50 percent of its pore volume from pores angstroms or larger in pore diameter, or have an average pore diameter of about 100 angstroms.

For high metals content feedstocks, larger pore diameters are desired for the hydrotreating catalyst used in zone 4. In many instances, it is advantageous to have a substantial amount of macropores in the catalyst used in zone 4, macropores being defined herein as pores having a diameter greater than about 500 angstroms. When using the catalyst in zone 4 in one or more fixed catalyst beds, as opposed to fluidized or ebulated catalyst beds, it is particularly preferred to use the macroporous catalyst in the uppermost part of the fixed hydroconversion catalyst bed as described in more detail in the previously mentioned applications, Ser. Nos. 2,096 and 2,097.

Preferably, a large amount of the catalyst used in hydroconversion zone 4, for example, 40 percent or more of the catalyst, is catalyst which has a high activity for both hydrodesulfurization (usually requiring a surface area of at least 100 m.2/g., and preferably at least 200 m.2/ g.) and hydrodemetallaton, as well as having a relatively high capacity for demetallation. As indicated previously, preferably the catalyst has at least .50 percent of its pore volume from pores 100 angstroms or larger in pore diameter. For feedstocks to the hydrotreating step having a metals content greater than 20 parts per million, the high desulfurization activity, high demetallation activity and capacity catalyst preferably has at least 50 percent of its pore volume from pores angstroms or larger in pore diameter. For residua feedstocks having 35 parts per million metals or more, the catalyst preferably has at least 50 percent of its pore volume from pores 150 angstroms or larger in pore diameter. I have found that in using expanded catalysts of high hydrodesulfurization activity, and high hydrodemetallation capacity, and activity, between 25 and 95 percent of the sulfur present as organic sulfur in the residuum feed to the hydrotreating step can be converted to HZS, and then easily removed from the feed so that subsequent coking of the 900 F.1-lor 1000 F.-i eluent fraction from hydrotreating can be coked to give a relatively low sulfur and low metals content coke and surprisingly high liquid hydrocarbon coking yields.

Preferred operating conditions for the hydrotreating step of the present invention include a temperature between 600" F. and 850 F., pressure between 500 and 5,000 p.s.i.g., a hydrogen rate between 100 and 10,000 standard cubic feet of hydrogen per barrel of feed, and a liquid hourly space velocity between about 0.1 and 10.0.

According to the preferred embodiment shown in the drawing, the eifluent from hydrotreating zone 4 is passed via line 8 to fractionation zone 10. Fractionation zone 10 is used to distill relatively light hydrocarbons including gasoline boiling range hydrocarbons and gas oil boiling range hydrocarbons from the hydrotreating zone effluent as well as from the effluent .from coking zone 11. The gasoline fraction is indicated as removed via line 12 and the gas oil fraction via line 13. Light gases can be removed Via line `14. The gas oil fraction can be one or more cuts or hydrocarbon fractions such as: light gas oil (1h00-600 F. boiling range), medium gas oil (500-800 F.), and heavy gas oil (650-l000 F.). The gas oil fractions withdrawn via lines 12 and 13 are particularly attractive feedstocks to catalytic cracking and/ or hydrotreating to produce gasoline and/or jet fuel. In the process of the present invention, streams 12 and 13 have a relatively high aniline point and low aromaticity, as is shown in more detail by Example I hereinbelow.

Fractionation zone 10, according to the preferred embodiment, advantageously can serve to separate a heavy gas oil fraction which typically would be separated from vacuum residuum by a large and expensive vacuum drstillation step applied to the reduced crude obtained from the atmospheric distillation column used in zone 2. i

Fractionation zone can contain t-wo or more distillation columns operating in series, but usually fractionation zone 10 basically consists of a large fractionation column with multiple cuts being removed from the column. The lower heavy cut from the fractionation zone can be a l000 F.|- boiling range fraction for feed via line 15 to coking zone 11.

The coking temperature usually is between about 700 F. and l100 F. Coking in zone 11 can be, for example, uid coking or delayed coking, although delayed coking is preferred.

Fluid coking is described in Petroleum Refner, vol. 39, No. 5, May 1960, pages 157-160.

In delayed coking, the heavy hydrocarbon feed typ1- cally passes from the bottom of a fractionator column to a furnace wherein it is heated to a temperature sufficient for heavy oil cracking. The heated heavy oil is introduced to an insulated drum where the residence time is sufficient for coke to form and settle from the mixture. Suitable operating conditions for delayed coking in zone 11 include a furnace outlet temperature between about 850 F. and 950 F., a coke drum temperature between about 750 F. and 850 F., and a coke drum pressure between about 10 and 70 p.s.i.g.

When coke boils up to a predetermined level in one of the coke drums for a delayed coking unit, flow is diverted to another drum so that the furnace operation is continuous. Thus, the drums are operated in pairs with one on-stream while the other is being dumped. A full coke drum is removed from the process ow, steamed to strip light hydrocarbons from the coke, and cooled by water injection. Various means have been used to remove the coke from the coke drums with recent designs using high pressure (over 1000 p.s.i.g.) water jets to cut thecoke from the drum.

According to that preferred embodiment of the process of the present invention wherein delayed coking is used in zone 11, hot vapors from the coking drum are returned to fractionation Azone 10 via line 18 and 25. The hot vapors introduced via line 25 to zone 10 serve to aid in the stripping of the heavy material removed from hydrotreating zone 4 via line 8. As indicated previously, gasoline boiling range hydrocarbons and gas oil boiling range hydrocarbons are removed from the fractionation zone via lines 14, 12 and 13. Heavier material present primarily in the hydrotreating zone eluent, but also in the vapors removed via line 18 from coking zone 11, are removed via line from the common fractionation zone and fed to coking zone 11. The hot vapors withdrawn from coking zone 11, via line 18, can be fed to hydrotreating zone 4 (usually after condensation and some fractionation) via lines 21, 22, and 3 instead of feeding this portion of the coking zone effluent to fractionation zone 10. Some fractionation facilities can form a portion of coking zone 11 so that product hydrocarbons are withdrawn via lines 17, 16, and 18. Thus, heavier gas oil hydrocarbons can be withdrawn via line 18, medium boiling range hydrocarbons via line 16, and then recycled, for example, to hydrotreating zone 4 via lines 20, 22, and 3, and light gaseous hydrocarbons via line 17.

Gaseous hydrocarbons also are usually withdrawn from hydrotreating zone 4, as is schematically indicated at line 23.

8 EXAMPLES Table la shows a liquid volume yield of C5-lmaterial of coking of 1000 R+ residuum of 76.8%. Table lb shows a C5| vol. percent yield of 86.4% from coking of hydrotreated 975 R+ residuum. Thus, the yield from the hydrotreated residuum was about 10 percent greater than the yield from the non-hydrotreated residuum. The hydrotreating catalyst used for hydrotreating the residuum ahead of the coking step was one in accordance with the process of the present invention, i.e., a hydrotreating catalyst having more than 50 percent of its pore volume in pores larger than angstroms in diameter. Furthermore, the hydrotreating catalyst was a catalyst formed by a cogelation preparation plus the use of a procedure to obtain an expanded catalyst, i.e., a catalyst with increased average pore sizes, not merely increased porosity. In particular, the average pore diameter of the catalyst used Was greater than angstroms.

T he catalyst used for the hydrotreating step in the above examples was prepared in accordance with the procedure described in U.S. Pat. 3,493,517 for the production of a hydrotreating catalyst comprising discrete metal phosphate particles in a continuous phase matrix of other catalyst components such as Group VI compounds including molybdenum or tungsten and Group VIII compounds including nickel or cobalt. Furthermore, the catalyst was expanded using a high molecular weight detergent according tothe process described in Ser. No. 3,239 for obtaining catalysts with a substantial amount of large pores, but yet with a relatively high hydrodesulfurization and hydrodemetallation activity. The average size of the pores in the catalyst used in Example I above was about angstroms.

Referring again more particularly to the series of tables for Example I, the question can be raised as to the comparability of the C5 liquid yield from the non-hydrotreated 1000 R+ fraction versus the hydrotreated 970 F.4- fraction in view of the fact that the 975 F.| fraction included 25 F. of material boiling below the material in the 1000 F.-{ fraction. That is, it is diflicult to estimate how much of the 975 F. to 1000 F. portion would go to light gases and coke in the coking step and how much would go to the formation of C5-iliquid.

Table 1c of Example I shows the yields for C54- liquid on the basis of whole crude. Column l in Table le shows a C5+ liquid yvolume yield of 43.4% for hydrotreating followed by 975 F.+ coking in accordance with the present invention.

Table lc, column 2, shows a C54- liquid yield of 38.3 for coking a 750 R+ feedstock.

Column 3 of Table 1c shows a yield of 39.6% C5+ liquid for coking a 1000 F.+ residuum and adding in the C54- liquid fraction, represented by the 750 to 1000 F. boiling range vacuum gas oil.

lColumn l of Table 1c is thus directly comparable to columns 2 and 3 as all three columns show the yield of C5-{ liquid material in the 750 R+ fraction except that the processing lwas different for the respective columns, as indicated in the headings for the respective columns. It is seen that the C5+ liquid yield is about 4 vol. percent higher on the basis of whole crude and about 10% higher on the basis of 750 R+ fraction. This is a surprising and unexpected increase in C5+ liquid yield which I have found is achieved in accordance with the process of the present invention.

It may also be noted in comparing column 2 to column 3 of Table lc that the amount of C5+ liquid produced from coking decreases when the boiling point of the material to the coking step is lower. In column 2 the C5+ liquid is 38.3 vol. percent for the coking of 750 F.4- residuum. In column 3 the yield is 39.6y for the coking of 1000 F.{ residuum with the 750 to l000 F. material added back in so that the C5+ liquid yield is on the basis of 750 R+ material has a net overall yield as a percent of whole crude. Thus, it appears that when the feedstock to the coking step is of a lower boiling point more material goes to light gases and coke than when the coking feedstock is of a higher initial boiling point. This indicates that the improved results in C54- liquid yield obtained in accordance with the process of the present invention are not a result of the lower boiling point of the feedstock to the coking step. (The comparative examples used do not have exactly the same boiling point cut point because the examples were generated from experimental data which was obtained previous to my finding of the unexpected advantage obtained in accordance with the process of the present invention.)

The data in the second example, which is presented by Tables 2a and 2b, further supports the unexpected advantage achieved in accordance with the process of the present invention. Example 2 also demonstrates that the process of the present invention applies to a variety of heavy hydrocarbon feedstocks. The process of the present invention, as indicated earlier, is preferably applied to feedstocks containing asphaltenes, and usually also contain 10 a substantial amount of organometallic compounds. In general, the feedstock will contain at least 50% by volume of material boiling above 600 F. The feedstock also will usually have at least 2 vol. percent asphaltenes, that is, heavy hydrocarbon material which is not soluble in pentane.

The data presented in Example I shows that a higher aniline point is achieved for the products from the cokng step using the process of the present invention than when material is coked without using the process of the present invention. In Table la the aniline point of the 450 to 650 F. gas oil is 125, Whereas in Table 1b in accordance with the present invention it is 138. Also, the aniline point for the 650 F.| material in Table 1a is 153, Whereas the `650 R+ maetrial -for the coking of hydrotreated 975 F. residuum in Table 1b is 170. The higher aniline points indicate more aromaticity. The lower aromaticity feedstocks are better catalytic cracking feedstocks, and also are -better feedstocks for hydrocracking to produce jet fuel or gasoline.

TABLE 1e., EXAMPLE I-ALASKAN NORTH SLOPE CRUDE Coking nonhydrotreated (straight run) residua l Coking, 750 F. plus residuum Coking, 1,000 F. plus residuum Straight run residuum feed Product Product 650 F.| 650 F.+ 750 F. 1,000F. -l- Yield Coke 40G-650 F. gas oil Yield Coke 40o-650 F. gas oil Yield to crude, vol. percent (wt. percent) 44. 6 9. 54 5. 66 8. 22 Gravity, API 14. 0 31. 7 32. 6 21.0 Sulfur, wt. percent 1. 7 1. 13 1. 22 1. 48 Nitrogen, 3, 880 800 870 4, 100 Conradson carbon, wt. percent 9. 0 0. 5 n-Pentane insolubles (asphaltenes),

Wt. percent 4. 3 Viscosity, cs./210 F 80 Metals, p.p.m:

FB ..-'.-L. 2.5 5 15 18 Ni-. 24 49 135 170 V 38 80 220 280 UOP K/an1 e point, F-, 11.60/ /126 /165 /125 [153 Aspheltene out:

Wt. percent residuum.- 7. 7 n Sulfur, wt. percent 3. 0 Metals, ppm.:

Fe 52 Ni 310 V 450 Ashpaltene-ree cut:

Wt. percent of resrduum. 92.3 Sulfur, wt. percent 1. 98 Metals, p.p.m.:

Fe" N1 t Y Ni 26 50 Coking yields:

Coke, wt. percent (3i-gas wt. percent Cri-liquid, Wt. percent Orl-liquid, vol. percent 40o-650 F., vol. percent 650 F. plus gas oil, vol. percent l Temperature, 760890 F., pressure, 15 p.s.i.a.

TABLE 1b, EXAMPLE I-ALASKAN NORTH SLOPE CRUDE Coking hydrotreeted residua 1 Coking hydrotreated 975 F. Straight run residnum feed hydrotreating 750 F-lresiduum 2 plus residuum Product Product 975 F.- 975 F.'

acira- 5- 800- 4G0- 650 F.+ 750 F.|` tion tion Yield 800 F. 975 F 975 Frl- Yield Coke 650 F gas Oil Yield to crude, vol. percent (wt percent). Gravity, API- Sulfur, Wt. percen Nitrogen, p.p.m- Conradson carbon, Wt n-Pentane insolubles (asphalten V UOP K/anlne point, F Asphaltene eut:

Wt. percent of residuum Sulfur, wt. percent Metzlils, p.p.m.:

TABLE 1b, EXAMPLE I-Coiitinued Coking hydrotreated residua 1 Coking hydrotieated 975 F.

Straight run residuum feed hydroticating 750 F-iresiduum 2 plus residuum Product Product 975 F.- 975 F.}

fraciiac- 05- 800- 400- 650 F.+ 750 F.+ tion tion Yield 800 F. 975 F. 975 F.+ Yield Coke 650 F. gas oil Asphaltene-free out:

Wt. percent of reslduum. Sulfur, wt. percent-...

V Coking yields:

Coke, wt. percent v 04-gas, wt. percent.-- Cri-liquid, wt. percent- 05+liquid, vol. percent.-. 40G-650 F. vol. percent... 650 F-i-gas oil, vol. percen Hydrotreating yields:

H2 cons., s.c.f./b 05-750" F., vol. percent. 750-975 F., vol. percent 975 F.-I, v01. percent 975 F.+, wt. percent 1 Temperature, 760890 F.; pressure, 15 p.s.i.a. 2 Temperature, 750 F.; 0.6 LHSV; pressure, 2,400 p.s.i.g.; 2,000 s.c.f./b. H2, rec.

TABLE 1 EXAMPLE I SUMMARY 0F YIELDS Although various embodiments of the invention have Hydro. 1 Oogglirf been described, it is to be understood that they are meant treating stmight to be illustrative only and not limiting. Certain features 750 Fl run remay be changed without departing from the spirit or scope 30 asug gfff sduldg of the present invention. It is apparent that the present inhydggtgep Straight 750-1,000 F- vention has broad application to a combination process gvemuyield as percent of product residurf vagclslr involving asphaltene hydroconversion followed by coking wherein a catalyst of relatively large pore sizes is used in 6. i ggg gplff'f VOL percent ggf@ 39% 35 the hydrotreating step. Accordingly, the invention 1s not to glflfoy gl- Prccetyltf gg gi; be construed as limited to the specific embodiments or eX- 650 R+ s culled, per@ 3111 22' 5 31' 1 amples discussed but only as defined in the appended claims or substantial equivalents of the claims.

TABLE 2a, EXAMPLE Ii-ARABIAN LIGHT CRUDE Coking hydrotreated residuum Coking nonhydrotreated residuum Straight- Straiglit run atmos- Hydrotreatlng 'l' Coking 650 F.hydro run atmos- Coking l pheiic -f----- treated residuuin l pheric (-665 F+) Product (-685 F.+) Product residuum, Product residuum, feed t0 feed to 05+ hydrotreatl 05+ Cia-l- 650 coking Yield Coke liquid ing Yield liquid 650 F.+ Yield Coke liquid F.+

Yield to crude, vol. percent (wt. o

percent) as (43.9) (7. 94) {(gj 40. 5(45. 2)'{ Gravity, API---- 16 33.6 17.3 Sulfur, Wt. percent 3. 1 5. 8 3.0 Conradson carbon, wt. percent.. 8. 2 7. 6 Metals, p.p.m., Ni/V 10/29 9/27 Coking yields:

Coke, wt. percent 18.1 Cyl-liquid, wt. percent- 74. 6 Cyl-liquid, vol. percent- 83. 5 Ci-gas, wt. percent 7. 3 Hydrotreating yields:

05+, vol. percent 102.1 05+', wt. percent 97. 5 350-650l F., vol. percent 17. 4 650 F-|- vol. percent 83.5 650 F.+, wt. percent.. 80. 8

(Feed to coking 1 W50-900 F. temperature; 15 p.s.i.a. pressure. 2 715 F. temperature; 0.75 LHSV; 1,700 p.s.i.g. pressure.

TABLE 2b, EXAMPLE rI-sUMMARY or YiELDs What 1S Clalmed 1S:

(Arabian Light Crude) 65 1. A process for obtaining increased normally liquid BaSiS1405 v01- percent residuum yield from crude hydrocarbon yields from coking a hydrocarbon feed con- Coking residu. Hydrotreaung taining `at least 3 parts per million metals which process um (39 iol 40.5 v01t comprises: cmdefffrdg. residufcd '(a) contacting the feed, at elevated temperature and 111g Ggf Cokipfrol; 70 pressure and in the presence of added hydrogen, with Net overall yields as percent oi vol. percent hydrotreated a hydrotfeatmg `catalyst CO'lnPl'lsmg Group VI and Crude 0f Crude) Product Group VLII metals and an inorganic refractory base Coke, w1 percent 7 94 .1 38 and having at least 50 percent of its pore volume from C5 liquid, wt. percent- 34.0 38.4 C5 liquid, VOL percent 34.1 30 l pores 100 angstroms or larger in pore diameter to 75 obtain a hydrotreated feedstock, and

(b) coking at least a portion of the hydrotreated feedstock at a temperature between 700 F. and 1100 iF. to obtain solid coke and vaporized normally liquid hydrocarbons.

2. A process in accordance with claim 1 wherein at least 50 percent of the pore volume of the hydrotreating catalyst is from pores 130 augstroms or larger in pore diameter, and wherein the hydrocarbon feed contains at least parts per million metals.

3. A process in accordance with claim 1 wherein the hydrotreating catalyst is produced so as to have larger average pore diameters by a process which comprises:

(a) forming a hydrogel comprising at least one inorganic compound,

(b) adding a detergent to the hydrogel, and

(c) carrying out at least part of the drying of the hydrogel after the detergent is added to the hydrogel.

4. A process in accordance with claim 1 wherein the hydrocarbon feed contains organic sulfur compounds, and between and 95 weight percent of the sulfur present as organic sulfur compounds is converted to hydrogen sulfide during the hydrotreating of the feedstock.

5. A process in accordance with claim 4 wherein the hydrotreating catalyst has a surface area of at least 200 m.2/g. of catalyst.

6. A process in accordance with claim 1 wherein at least a portion of the hydrotreated feedstock is subjected to delayed coking at a coke drum temperature between about 750 `F. and 950 F.

7. A process in accordance with claim 1 wherein the hydrotreating catalyst comprises (a) a carrier comprising at least one component selected from silica and alumina, and at least one hydro` ygenating component selected from Group VI metals and compounds thereof, and Group VIII metals and compounds thereof, and

(b) discrete, substantially insoluble metal phosphate lparticles (l) dispersed in said carrier,

(2) consisting essentially of at least one metal phosphate selected from phosphates of zirconium, titanium, tin, thorium, cerium and hafnium,

(3) containing substantially the entire phosphorus content of said catalyst, and

(4) containing phosphorus in an amount of 3 to 15 weight percent of the total catalyst, expressed as P205.

8. A process for obtaining increased normally liquid 14 hydrocarbon yields from delayed coking of a hydrocarbon residuurn feed containing at least 35 parts per million metals present as soluble organometallic compounds in the hydrocarbon feed which comprises:

(a) contacting the feed at a temperature between 600 P. and 850 EF., and a pressure between 500 and 5,000 p.s.i.g., and in the presence of 10G-10,000 standard cubic feet of hydrogen per barrel of feed with a hydrotreating catalyst comprising Group VI and Group VIII metals, and an inorganic refractory base with said catalyst having at least percent of its pore volume from pores angstroms or larger in pore diameter to obtain a hydrotreated feedstock, and

(rb) subjecting the hydrotreated feedstock to delayed coking at a coke drum temperature between about 700 CF. and 900 F. to obtain solid coke and vaporized normally liquid hydrocarbons.

9. A process in accordance with claim 1 wherein the hydrocarbon feed to the hydrotreating step is a long residua feed obtained without vacuum distillation of a crude oil, and wherein the hydrotreated feedstock is fed to a coker fractionator wherein hydrocarbon components are stripped and fractionated from the hydrotreated feedstock before the hydrotreated feedstock is fed to the coker, and wherein at least a portion of the vaporized normally liquid hydrocarbons from the coking step are fed to the coker fractionator 10. A process in accordance with claim 9 wherein vaporized normally liquid hydrocarbons from the coking step are used to aid in stripping and fractionating hydrocarbons boiling below 900 F. from the hydrotreated feedstock in the Coker fractionator.

References Cited UNITED STATES PATENTS 2,871,182 1/ 1959 Weekman 208-50 2,882,221 4/ 1959 lDinwidde et al 208-111 2,963,416 12/1960 Ward et al. 208--50 3,451,921 `6/ 1969 .lanes 208-46 3,622,500 11/ 1971 Alpert et zal 208-111 DELBERT E. GANTZ, Primary Examiner G. SOHMITKONS, Assistant Examiner US. C1. XR. 

